<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    canvas {
      border: 1px solid #000;
    }
  </style>
</head>

<body>
  <canvas width="300" height="300"></canvas>

</body>
<script>
  let canvas = document.querySelector("canvas")
  let ctx = canvas.getContext("2d")

  ctx.translate(150, 150)
  // ctx.arc(0, 0, 100, 0, 2 * Math.PI)

  //  PI ---> 180度
  //   Math.PI/180*54  -----> 54度
  //   Math.PI/180*270     ---->   270度
  //  2PI---> 360度
  // ctx.arc(0, 0, 100, 0, Math.PI,false)
  ctx.arc(0, 0, 100, 0, Math.PI/180*270,true)
  ctx.stroke()




</script>

</html>